JP2012186860A - Imaging device, method of controlling the same, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress bad influences caused by disturbance of light exposure amount resulting from diaphragm control.SOLUTION: An imaging device has: an imaging unit accumulating electric charges depending on an incoming light amount and outputting an image signal; a diaphragm controller controlling an aperture size of a diaphragm that adjusts the incoming light amount to the imaging unit; and a controller, in the case that an operation for adjusting the aperture size of the diaphragm is performed on the basis of the control of the diaphragm controller in a charge accumulation time period of the imaging unit in an operation for sequentially displaying a plurality of images based on the image signals outputted from the imaging unit on a display device, performing control so that processing that is performed by using the image signal based on the electric charges accumulated by the imaging unit is not performed by using the image signal based on the electric charges accumulated in the charge accumulation time period in which the operation for adjusting the aperture size of the diaphragm has been performed.

Description

  The present invention relates to an imaging apparatus such as a digital camera or a video camera, and more particularly to an imaging apparatus that continues to display a subject image with an electronic viewfinder.

  Conventionally, in a diaphragm mechanism for controlling the aperture of a lens, a plurality of diaphragm blades are physically moved in order to control the aperture amount. Therefore, as the aperture amount is controlled to be large, the time required for aperture control becomes longer.

  In addition, in an electronic camera equipped with an electronic viewfinder, when the charge accumulation time control, sensitivity control, and aperture control of the image sensor are performed almost simultaneously to adjust the exposure amount, the charge accumulation time control and sensitivity control of the image sensor are The settings can be switched instantly for electronic control. However, since the diaphragm control involves physical driving of the diaphragm blades, the control time varies depending on the opening control amount. Due to these control time differences, for example, when changing the lens aperture while keeping the exposure amount appropriate, the charge was accumulated between the completion of the charge accumulation time and sensitivity setting change and the completion of aperture control. The exposure amount of the image signal is disturbed.

  FIG. 3 is a diagram schematically showing changes in aperture control and charge accumulation control timing and exposure amount. In order from the top in FIG. 3, the charge is obtained by accumulating timing of three frames in the aperture control period, aperture control starting in the middle of frame 1 and completing in the middle of frame 3, and control for aperture stop starting in the middle of frame 1. The charge accumulation control with a long accumulation time is shown. The bottom row shows the exposure amount in the charge accumulation control.

  In FIG. 3, in frame 1, the exposure amount gradually decreases with the start of aperture control, and the exposure amount in frame units slightly falls below a desired level. Further, in frame 2, although the charge accumulation control is changed to a new setting for extending the charge accumulation time, the aperture control is not completed, and thus the exposure is excessive. In frame 3, although the aperture control has not ended, the aperture value has already approached the set aperture value.

  When the stored image is continuously displayed on the electronic viewfinder, if the overexposed frame 2 is displayed after the slightly exposed frame 1, it is visually recognized as flicker due to a sudden luminance change.

  Patent Document 1 proposes a technique for suppressing the above-described flicker associated with aperture control. In the technique disclosed in Patent Document 1, when the electronic viewfinder is displayed, the aperture blade drive speed (aperture control speed) is decreased to suppress the exposure setting change. By operating in this way, the disturbance of the exposure amount is reduced and the display flicker is suppressed.

Japanese Patent Laid-Open No. 03-10576

  However, as described in Patent Document 1, if the aperture control speed is slowed down, it takes a long time to reach the target value in controlling the exposure amount. For example, when chasing a moving subject, the brightness of the subject frequently changes as the lighting conditions of the subject change. If the aperture control is slow at that time, a state that does not match the target exposure amount will continue.

  Further, in a lens-interchangeable electronic camera, when a lens whose aperture control speed cannot be changed is attached, display flicker accompanying aperture control cannot be suppressed.

  In addition, fluctuations in exposure amount due to aperture control not only cause display flicker, but also include automatic exposure control (AE) in which operation is controlled according to the result of charge accumulation, focus detection (AF) in contrast evaluation methods, automatic This also affects white balance control (AWB) and output signal gain control. Further, it also affects the individual adjustment work of the image signal level at the time of factory shipment or service support. In such a situation, the method described in Patent Document 1 has a problem in that the disturbance of the luminance signal as a result of charge accumulation cannot be suppressed, and the control is adversely affected.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an imaging apparatus and a control method therefor that can suppress an adverse effect caused by exposure amount disturbance accompanying aperture control.

  In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention includes an imaging unit that accumulates electric charges according to the amount of incident light and outputs an image signal, and an amount of light incident on the imaging unit. A diaphragm control means for controlling the aperture amount of the diaphragm to be adjusted; and the diaphragm control means during the charge accumulation period of the imaging means during operation for sequentially displaying a plurality of images based on the image signals output from the imaging means on the display device When the operation of adjusting the aperture of the diaphragm is performed based on the control of the aperture, the operation of adjusting the aperture of the aperture is performed using the image signal based on the electric charge accumulated by the imaging unit. And control means for performing control so as not to use an image signal based on the charge accumulated during the charge accumulation period.

  The image pickup apparatus control method according to the present invention controls an image pickup means for accumulating charges according to the amount of incident light and outputting an image signal, and an aperture amount of a diaphragm for adjusting the amount of light incident on the image pickup means. And a diaphragm control means for controlling the imaging device, wherein the display means sequentially displays a plurality of images based on the image signals output by the imaging means during the charge accumulation period of the imaging means during operation. When the operation of adjusting the aperture amount of the aperture is performed based on the control of the aperture control means, the processing performed using the image signal based on the electric charge accumulated by the imaging means is adjusted. And a control step of performing control so as not to use an image signal based on the accumulated charge in the charge accumulation period in which the operation is performed.

  According to the present invention, it is possible to suppress an adverse effect due to exposure amount disturbance accompanying aperture control.

It is a block diagram which shows the structure of the digital camera concerning one Embodiment of this invention. It is a flowchart explaining operation | movement of the digital camera of one Embodiment. FIG. 6 is a diagram schematically showing changes in aperture control and charge accumulation control timing and exposure amount.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a digital camera as an imaging apparatus according to an embodiment of the present invention.

  The digital camera 100 includes a lens group 101 that forms a subject image by forming a light beam from a subject, and a lens control unit 102 that controls the position of a focus lens (not shown) included in the lens group 101. In addition, a diaphragm 103 that adjusts the amount of incident light from the lens group 101 and a diaphragm controller 104 that controls the aperture of the diaphragm are provided. The aperture control unit 104 notifies the imaging signal control unit 112 (described later) of the timing for starting and completing aperture control.

  Furthermore, the digital camera 100 includes an image sensor 105 that includes a CMOS sensor that photoelectrically converts a subject image formed by the lens group 101, and an image sensor drive control unit 106 that controls accumulation timing and signal gain of the image sensor 105. .

  Further, the digital camera 100 includes a focus detection unit 107 that performs contrast detection based focus detection based on an image signal obtained by the image sensor 105 and determines the focus position of the lens 101.

  Further, the digital camera 100 includes an exposure control unit 108 that sets the aperture amount of the diaphragm 103, the charge accumulation time of the image sensor 105, and the signal gain based on the image signal obtained by the image sensor 105.

  Furthermore, the digital camera 100 includes an AWB (auto white balance) adjustment unit 109 that calculates a white balance coefficient used in an image processing unit 110 described later based on an image signal obtained by the image sensor 105.

  Further, the digital camera 100 performs color gain correction processing based on the white balance coefficient calculated by the AWB adjustment unit 109 for the image signal obtained by the image sensor 105, and resizing for adjusting to a desired image size. An image processing unit 110 that performs resampling is provided.

  Furthermore, the digital camera 100 includes an image signal individual adjustment unit 111 that performs output adjustment for each individual image signal in order to correct manufacturing quality variations of the image sensor 105.

  Furthermore, the digital camera 100 includes an imaging signal control unit that controls output of an image signal from the imaging element 105 to the focus detection unit 107, the exposure control unit 108, the AWB adjustment unit 109, the image processing unit 110, and the image signal individual adjustment unit 111. 112. The imaging signal control unit 112 includes a timing for starting and ending aperture control notified from the aperture control unit 104 (aperture control timing information), and a timing for starting and ending charge accumulation notified from the imaging element drive control unit 106. (Charge accumulation timing information) is input. From the input notification, the imaging signal control unit 112 monitors whether the diaphragm 103 is driven during the charge accumulation period. Based on the monitoring result, the imaging signal control unit 112 outputs the output image signal of the imaging element 105 as the focus detection unit 107, the exposure control unit 108, and the AWB adjustment unit 109 if the driving of the diaphragm 103 is mixed in the charge accumulation period. The image processing unit 110 and the image signal individual adjustment unit 111 are controlled not to output them.

  Furthermore, the digital camera 100 includes a remote control unit 113 that communicates with an external device such as a computer and receives operation commands for focus detection, exposure control, white balance control, and individual adjustment.

  Further, the digital camera 100 displays the image data output from the image processing unit 110 as one frame of a live view image, a still image, or a moving image, or an EVF (electronic viewfinder) that displays the camera state such as exposure. The unit 114 is provided.

  Further, the digital camera 100 includes a recording unit 115 that records the image data output from the image processing unit 110 as a frame of a live view image, a still image, or a moving image on a recording medium such as a semiconductor memory or an optical disk.

  The digital camera 100 also includes a camera control unit 116 that controls the entire digital camera 100 and executes various operations such as focus detection, exposure control, white balance control, individual adjustment, and remote operation permission / denial.

  FIG. 2 is a flowchart showing the operation of the digital camera 100 of the present embodiment. This operation is executed according to a computer program stored in a memory (not shown) in the camera control unit 116.

  First, the camera control unit 116 causes the image sensor 105 to start a charge accumulation operation when the power is turned on, and causes the EVF unit 114 to display a live view image signal generated by the charge accumulation.

  Here, immediately after the power is turned on, the camera control unit 116 performs the operations of Steps S201 to S211 described below without making any determination. However, after the operation of step S201 to step S211 is performed once, the operation of step S201 to step S211 is performed only when the diaphragm drive is not mixed in the charge accumulation period of the image sensor 105 according to the determination of step S213. Do. In other words, when aperture driving is mixed in the charge accumulation period, white balance adjustment processing, live view image update processing (display processing), focus detection processing, which are operations in steps S201 to S211, Do not perform exposure control or individual adjustment.

  First, in step S <b> 201, the image sensor drive control unit 106 determines whether or not it has entered a timing (accumulation blanking period) that is a boundary of the charge accumulation operation for each frame in the image sensor 105. If it is in the accumulation blanking period, the process proceeds to step S202. If not, the process returns to step S201.

  In step S202, the camera control unit 116 determines whether to perform white balance control.

  If white balance control is to be performed, the process proceeds to step S203. When the white balance control is not performed, the process proceeds to step S204.

  Here, in the second and subsequent loops of this flowchart, the flow proceeds to the flow after step S201 only when the aperture drive is not mixed in the charge accumulation period in step S213. Therefore, in step S203, the aperture drive is performed during the charge accumulation period. Is not mixed.

  Therefore, in step S <b> 203, the image signal obtained by the imaging element 105 is output to the AWB adjustment unit 109 and the image processing unit 110 in accordance with the control of the imaging signal control unit 112. The AWB adjustment unit 109 receives an image signal and calculates a white balance correction value of the image. The calculated white balance correction value is output to the image processing unit 110. After output, the process proceeds to step S204.

  In step S204, the camera control unit 116 determines whether to update the live view display image of the EVF unit 114. When an operation input prohibiting live view display (for example, pressing a dedicated button) is input, or when the remote control unit 113 receives a notification prohibiting live view display, the following is performed. . That is, the camera control unit 116 switches the EVF unit 114 to display the exposure information set by the exposure control unit 108, the recording status of the recording unit 115, or the recording data itself. In this case, since the image obtained by the image sensor 106 is not displayed on the EVF unit 114, it is determined that the live view display image is not updated. Otherwise, it is determined that the display image is updated. When updating, it progresses to step S205. When not updating, it progresses to step S206.

  In step S205, as already described, since the driving of the diaphragm 103 is not mixed in the charge accumulation period of the image signal obtained by the image sensor 105, it is obtained by the image sensor 105 according to the control of the image signal control unit 112. The obtained image signal is output to the image processing unit 110. The image processing unit 110 performs resizing / resampling processing for adjusting the input image signal to an image size suitable for display by the EVF unit 114. If the white balance correction value is notified from the AWB adjustment unit 109 through the process of step S203, the image processing unit 110 performs color gain correction image processing based on the white balance correction value. New image data subjected to the above-described image processing is output to the EVF unit 114. The EVF unit 114 receives the input of image data and updates the display to the input image. After the update, the process proceeds to step S206.

  In step S206, the camera control unit 116 determines whether or not the focus detection unit 107 performs focus detection. When a focus detection request signal (for example, a signal output by pressing a dedicated button) is input or when a focus detection request notification is received by the remote control unit 113, the camera control unit 116 detects the focus. Judge that. Otherwise, the camera control unit determines not to detect focus. When focus detection is performed, the process proceeds to step S207. If focus detection is not performed, the process proceeds to step S208.

  In step S207, as described above, since the driving of the diaphragm 103 is not mixed in the charge accumulation period of the image signal obtained by the image sensor 105, it is obtained by the image sensor 105 according to the control of the image signal control unit 112. The obtained image signal is output to the focus detection unit 107. The focus detection unit 107 performs contrast evaluation on the input image signal, and determines a new focus position of the lens group 101 from the correspondence between the focus position of the lens group 101 and the contrast evaluation result. Then, a focus control command is notified to the lens control unit 102 through the camera control unit 116. After the notification, the process proceeds to step S208.

  In step S208, the camera control unit 116 determines whether or not the exposure control unit 108 performs exposure control. When there is an operation input for fixing at an arbitrary exposure (for example, pressing a dedicated button) or when the remote control unit 113 receives a notification of an arbitrary exposure setting, the camera control unit 116 controls the exposure. It is determined not to perform. Otherwise, the camera control unit 116 determines to perform exposure control. When performing exposure control, the process proceeds to step S209. If exposure control is not performed, the process proceeds to step S210.

  In step S209, as already described, since the driving of the diaphragm 103 is not mixed in the charge accumulation period of the image signal obtained by the image sensor 105, it is obtained by the image sensor 105 according to the control of the image signal control unit 112. The image signal is output to the exposure control unit 108. The exposure control unit 108 determines the charge accumulation time, signal gain, and aperture value of the image sensor 105 based on the luminance of the input image signal. The determined charge accumulation time and signal gain are notified to the image sensor drive control unit 106 and reflected from the next charge accumulation. The determined aperture value is notified to the aperture control unit 104 through the camera control unit 116. After the notification, the process proceeds to step S210.

  Here, the aperture control after notification will be described. When the determined aperture value is different from the current aperture value, the aperture controller 104 starts controlling the aperture 103. Since the diaphragm driving of the diaphragm 103 involves physical driving of the diaphragm blades, the timing at which the control of the diaphragm 103 is completed differs depending on the control amount of the diaphragm 103. Therefore, the timing at which the control of the aperture 103 is completed is not synchronized with the operation after Step S210, and the operation after Step S210 is executed without waiting for the completion of the control of the aperture 103. However, since the operations in steps S210 and S211 are performed based on the image signal of the frame before the aperture control is started, the operation of the aperture is not mixed in the charge accumulation period of the image signal. Will be done.

  In step S <b> 210, the camera control unit 116 determines whether to perform output adjustment (individual adjustment) for each individual image signal in order to correct variations in manufacturing quality of the image sensor 105. When an individual adjustment request signal (for example, a signal output by pressing a dedicated button) is input, or when an individual adjustment request notification is received by the remote control unit 113, the camera control unit 116 performs individual adjustment. It is determined that Otherwise, the camera control unit 116 determines not to make individual adjustments. In the case of individual adjustment, the process proceeds to step S211. When individual adjustment is not performed, the process proceeds to step S212.

  In step S211, as described above, since the driving of the diaphragm 103 is not mixed in the charge accumulation period of the image signal obtained by the image sensor 105, it is obtained by the image sensor 105 according to the control of the image signal control unit 112. The obtained image signal is output to the image signal individual adjustment unit 111. The image signal individual adjustment unit 111 determines a correction amount of the output level of the signal based on the input image signal. The determined correction amount of the output level is notified to the image sensor 105 and is reflected in the image signal level of the image sensor 105. After the notification, the process proceeds to step S212.

  In step S212, the camera control unit 116 determines whether to end the charge accumulation operation of the image sensor 105. When it is finished, the operation is finished. If not, the process proceeds to step S213.

  In step S213, the imaging signal control unit 112 determines whether or not the diaphragm 103 is mixed during the charge accumulation period based on the diaphragm control timing information and the charge accumulation timing information. If there is contamination, the process proceeds to step S214. If there is no contamination, the process proceeds to step S201.

  In step S <b> 214, the imaging signal control unit 112 determines whether or not it has entered a timing (accumulation blanking period) that is a boundary of the charge accumulation operation for each frame in the imaging element 105. If it is in the accumulation blanking period, the process proceeds to step S215. If not, the process returns to step S214 again.

  In step S <b> 215, it is determined whether the camera control unit 116 has received a notification of completion of control of the aperture 103. If the aperture control has been completed, the process proceeds to step S212, and if not completed, the process returns to step S215.

  The recording operation to the recording unit 115 is performed when an operation input for starting recording (for example, pressing of a dedicated button) is input or when a recording start request notification is received from the remote control unit 113. Done. Specifically, the image processing unit 110 outputs new image data subjected to image processing to the recording unit 115. The recording unit 115 records the input image data on a recording medium in a predetermined format.

  By the operation as described above, when the driving of the diaphragm 103 is mixed during the charge accumulation period, the image signal whose luminance has changed due to the disturbance of the exposure amount is subjected to white balance control, EVF display, focus detection of the contrast evaluation method, automatic exposure control, It is possible not to adversely affect individual adjustment.

(Other embodiments)
The object of each embodiment is also achieved by the following method. That is, a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded is supplied to the system or apparatus. Then, the computer (or CPU or MPU) of the system or apparatus reads and executes the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but the present invention includes the following cases. That is, based on the instruction of the program code, an operating system (OS) running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  Furthermore, the following cases are also included in the present invention. That is, the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion card or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the above storage medium, the storage medium stores program codes corresponding to the procedure described above.

100 Digital Camera 101 Lens Group 103 Aperture

Claims (9)

Imaging means for accumulating charges according to the amount of incident light and outputting an image signal;
Stop control means for controlling the aperture of the stop for adjusting the amount of light incident on the image pickup means;
An operation of adjusting the aperture amount of the diaphragm based on the control of the diaphragm control means during the charge accumulation period of the imaging means during the operation of sequentially displaying a plurality of images based on the image signal output by the imaging means on the display device Is performed, an image based on the charge accumulated in the charge accumulation period in which the operation for adjusting the aperture of the diaphragm is performed is performed using the image signal based on the charge accumulated by the imaging unit. Control means for controlling not to use signals,
An imaging apparatus comprising:   The control means opens the aperture of the aperture based on the control of the aperture control means during the charge accumulation period of the imaging means during the operation of sequentially displaying a plurality of images based on the image signal output by the imaging means on the display device. When the operation of adjusting the amount is performed, the processing performed using the image signal while the operation of adjusting the aperture amount of the aperture is performed based on the control of the aperture control unit is performed. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is controlled to use an image signal based on a charge accumulated in a charge accumulation period in which an operation for adjusting an opening amount is not performed.   The imaging apparatus according to claim 1, wherein the process performed using the image signal is a display process on the display apparatus.   The imaging apparatus according to claim 1, wherein the process performed using the image signal is an exposure control process.   The imaging apparatus according to claim 1, wherein the process performed using the image signal is a focus detection process.   The imaging apparatus according to claim 1, wherein the process performed using the image signal is a white balance adjustment process.   The imaging apparatus according to claim 1, wherein the process performed using the image signal is an output adjustment process of the imaging unit. A method of controlling an imaging apparatus comprising: an imaging unit that accumulates charges according to an incident light amount and outputs an image signal; and an aperture control unit that controls an aperture amount of an aperture that adjusts the amount of light incident on the imaging unit Because
An operation of adjusting the aperture amount of the diaphragm based on the control of the diaphragm control means during the charge accumulation period of the imaging means during the operation of sequentially displaying a plurality of images based on the image signal output by the imaging means on the display device Is performed, an image based on the charge accumulated in the charge accumulation period in which the operation for adjusting the aperture of the diaphragm is performed is performed using the image signal based on the charge accumulated by the imaging unit. A control method for an image pickup apparatus, comprising a control step of controlling so as not to perform using a signal.   A program for causing a computer to execute the control method according to claim 8.

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